SOI optical devices may include an active surface layer that includes waveguides, optical modulators, detectors, CMOS circuitry, metal leads for interfacing with external semiconductor chips, and the like. Transmitting optical signals from and to this active surface layer introduces many challenges. For example, a fiber optic cable may be attached to the SOI optical device and interface with a waveguide on its surface layer; however, the diameter of the one or more modes of the optic cable (e.g., approximately 10 microns for a single-mode cable) may have a much different size than the mode of a sub-micron dimensioned waveguide tasked with routing the optical signal in the SOI device. Accordingly, directly interfacing the fiber optic cable with the sub-micron waveguide may result in low transmission efficiency or high coupling loss.
To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one embodiment may be beneficially utilized on other embodiments without specific recitation.